The polyethylene plastic consists of polyethylene resin 100 weight portions, peroxide as cross-linking agent 0.2-2.5 weight portions, antioxidant 0.01-1.5 weight portions, auxiliary cross-linking agent 0.01-10 weight portions, lubricant 0.1-5 weight portions, and stuffing 0-80 weight portions. All the materials are mixed fully, the mixture is pelletized in an extruder at 80-190 deg.c, and the pelletized product is dried to water content less than 200 ppm and stored inside vacuum packing bag. When used, the pelletized material is extruded into pipe, wire or cable coating and hot radiation cross-linked in special infrared irradiation equipment to form cross-linked polyethylene product with excellent mechanical performance and heat performance.